1. Field of the Invention
The present invention relates to an assembly for supporting a stripper plate in a die set such that the stripper plate can be easily assembled and removed.
2. Brief Description of the Prior Art
Die assemblies include upper and lower die shoes. The lower shoe is adapted to be mounted on the bed of a punch press and the upper shoe is adapted to be mounted to a power ram for reciprocating the upper die shoe toward and away from the lower die shoe. Stamping a work piece is performed by suitable dies and punches mounted on the die shoes. One or more stripper plates complete the die set into a die assembly.
Stripper plates have long been used in die assemblies to strip the material being worked from the punches but stripper plates may perform other functions in addition to traditional stripping operations. These additional functions include retaining forming inserts, functioning as pressure devices, serving as guides for weak or thin punches, flattening parts, and so forth.
In the past, it has been customary, to mount the stripper plate on the die set by means of shoulder bolts extending through the upper or lower die shoe and screwing in to the stripper plate. The stripper plate is spring biased on the stripper bolts with springs that surround the shoulder bolts or are otherwise spaced between the stripper plate and the respective die shoe. During the operation of the press, breakdowns, the need to change punches, and the like, and other difficulties often require removal of the stripper plate. Stripper bolts that screw into the stripper plate are inconvenient as they require removing the die set from the press in order to remove the stripper plate.
Various means have been proposed to facilitate the removal of the stripper plate without removing the die set from the press. One such system makes use of a retaining screw which is threaded from the face of the stripper plate into a stripper spool, but with this system the stripper spool tends to spin with the retaining screw making installation and removal of the stripper plate difficult.
Flats have been provided on the stripper spool for the purpose of holding the spool while the retaining screw is threaded into the spool; however, lack of space in the die set makes access to the wrench flats very difficult or impossible. Spikes have been provided on the spool for digging into the rear face of the stripper plate to keep the spool from spinning with the retaining screw. When the stripper plate is reinstalled, the holes in the rear face of the stripper plate may not line up with the spikes. In time the spikes form a groove in which the spikes spin along with the spool. Another solution provides a projection on the head of the stripper spool which prevents the spool from rotating with the retaining screw but this requires the die shoe to be machined with an odd-shaped counterbore for receipt of the projection.
In view of the above, it is an object of the present invention to provide a stripper spool unit for supporting a stripper plate in a manner that the stripper plate can be removed for servicing the die without removing the die from the press. Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.
In accordance with the present invention, a stripper plate supporting assembly has a stripper spool with a shank, a head and a flat end remote from the head, with a drilled and tapped longitudinal hole extending inwardly from the flat end. A bore is provided in the flat end spaced from the drilled and tapped hole for receipt of a pin which is spring biased to normally project a free end of the pin beyond the flat end of the stripper spool. It will be understood that the terms xe2x80x9ca borexe2x80x9d and xe2x80x9ca pinxe2x80x9d as used herein includes the plural (i.e., one or more bores and/or one or more pins).
The assembly further includes a die set with a bore having a diameter for close sliding fit with the stripper spool shank and a shoulder for limiting the length of relative travel between the stripper plate and the die set. A stripper plate is provided with a bore in axial alignment with the drilled and tapped hole in the stripper spool. The stripper plate additionally has an opening or socket spaced from the bore for receipt of the free end of the pin. It will be understood that the term xe2x80x9can openingxe2x80x9d includes the plural (i.e., one or more openings).
A retaining screw extends through the stripper plate bore and threads into the drilled and tapped hole. The retaining screw coacts with the stripper spool to hold and support the stripper plate in position against the flat end of the stripper spool, with the free end of the pin received in the opening or socket in the stripper plate preventing the stripper spool from turning with the retaining screw, allowing the stripper plate to be easily and quickly positioned on and removed from the die set without removing the die set from the press.
The invention summarized above comprises the constructions hereinafter described, the scope of the invention being indicated by the subjoined claims.